1. Field of the Invention
The present invention relates to an image forming device such as a printer, a copying machine, a facsimile, or a multi-function device that includes several functions that require image formation, and more particularly to image forming device that includes a duct for discharging heat, ozone, and the like.
2. Related Art
Laser printers, copying machines, and other similar image forming devices include a photosensitive member. To form images, the surface of the photosensitive member is charged using a corona discharge. The charged surface is then exposed with light from a laser or a light emitting diode (LED). Exposed portions on the surface of the photosensitive member form an electrostatic latent image. The electrostatic latent image is developed by toner into a visual toner image. The toner image is transferred from the photosensitive member onto a recording medium such as paper. The toner image is thermally fixed onto the recording medium by a fixing device.
Various components used in the process generate heat. For example, a scanner motor is provided for rotating a polygon mirror to scan a laser beam across the surface of the photosensitive member. The scanner motor generates heat as it rotates the polygon mirror during image formation. Also the fixing device itself generates heat. A duct is provided in the image forming device to exhaust the heat to outside of the main body case 2.
In addition, ozone is generated from the corona discharge for charging the surface of the photosensitive member. Nitrogen oxide and silicon dioxide are also generated. Cation radicals are generated in the charge transfer layer of the photosensitive member when the charge transfer layer is exposed to a mixture of the ozone and nitrogen dioxide under a highly humid environment. The cation radicals deteriorate the charge transfer layer so that various electric characteristics of the charge transfer layer are reduced. For example, sensitivity and electric potential of the charge transfer layer are reduced and residual potential is increased. The poor electric characteristics adversely affect formation of the electrostatic latent image, so that image quality drops. A duct provided with a fan and an ozone filter is provided for removing ozone from the image forming device.
In order to make image forming devices more compact, the difference components are arranged in the main body case 2 within close proximity to each other. Also, high speed operation of image forming devices has increased the amount of heat generated by the components of the device. When the fixing device or other heat generating component is located close to a process cartridge, the heat from the fixing device can thermally affect the process cartridge. More specifically, the process cartridge holds toner that can deteriorate when heated. The deteriorated toner results in defective image formation.
An independent exhaust chamber is provided for discharging ozone. The exhaust chamber takes up space, so limits how compact the image forming device can be produced. The exhaust chamber needs to be opened and closed. Therefore, a movable member for opening and closing the exhaust chamber and also a drive source such as a solenoid must be provided. The image forming device becomes more complicated and expensive to produce.